`Empire', `Smoothee', `Jonagold', and `Rome Beauty' apple cultivars (CV) on five size-controlling rootstocks, Bud.9, M.9 EMLA, M.26 EMLA, Mark, and Ott.3, were planted in Fayetteville, Ark., in 1990 as a complete block design with six replications. Although interactions for several growth variables were observed in 1990–93, there were no cultivar–rootstock interactions in 1994, 1995, or for cumulative yield. After six seasons' growth, CV did not significantly affect any growth variable. Trees on M.26 and M.9 were the largest, while trees on Mark were significantly smaller for both tree height and TCA; trees on Ott.3 and Bud.9 were intermediate. `Smoothee' had the greatest cumulative yield, while both `Jonagold' and `Rome Beauty' had significantly less; `Empire' yield was intermediate. Trees on Ott.3 and M.26 had larger cumulative yields than other stocks, which were all similar. Trees on Mark had the greatest yield/TCA, while M.9 and M.26 had the least yield/TCA; Ott.3 and B.9 were intermediate. Trees on Mark had very high levels of foliar Mn and exhibited symptoms of Mn-induced internal bark necrosis.
Curt R. Rom and R. Andy Allen
Curt R. Rom, R. Andy Allen, and Bryan Blackburn
The Arkansas tree fruit research program has a history of involvement in rootstock development. The elements of rootstock development are rootstock cultivar testing and rootstock breeding and evaluation. Research is focused on apple and peach rootstocks. Rootstock testing is done in conjunction with the NC-140 cooperative uniform rootstock research project. Currently, there are 10 NC-140 trials in progress for apples, peaches, pears, and cherry rootstocks in Arkansas. The Arkansas rootstock breeding projects were established in the early 1970s as components of the fruit breeding program. The objectives are to develop apple and peach rootstocks which are adaptable to the Arkansas edaphic and adaphic conditions, have size control, have some degree of pest resistance, and are efficient in production. To date, 92 apple rootstock selections have been made and 41 are still in early evaluation for propagation and growth characteristics, while 56 peach rootstocks have been selected and are in early evaluation. Arkansas apple rootstocks selections are sequentially numbered with numbers preceded by AAR (ex: AAR-92). Peach rootstocks selections are numbered with numbers preceded by APR. Data from 2 NC-140 apple rootstock trials were presented and discussed.
Curt R. Rom, R. Andy Allen, Donn T. Johnson, and Ronald McNew
The NE-183 project was established in 1993 and the first trial planted in 1995 with the objective of evaluating new apple cultivars for horticultural, pest and disease resistance, and qualitative characteristics. Arkansas (AR) is the southernmost location for the initial planting. The following cultivars are in AR trial: `Arlet', `Braeburn', `Cameo', `Creston', `Enterprise', `Fortune', `Fuji', `Gala Supreme', `Ginger Gold', `GoldCrisp', `Golden Delicious', `Golden Supreme', `Goldrush', `Honeycrisp', `NY75414-1', `Orin', `Pristine', `Sansa', `Shizuka', `Suncrisp', `Sunrise', and `Yataka'. Bloom of `Braeburn', `Yataka', `Orin', `Gold Supreme', `Fortune', and `Enterprise' were early and may be exposed to annual spring frosts. The following cultivars ripened in July or August and may be too early for southern markets: `Pristine', `Sunrise', `Sansa', `Ginger Gold', `Arlet', `Honeycrisp', `Golden Supreme', and `Orin'. The following cultivars were very precocious and had yields >7.5 kg/tree in the third growing season: `Fuji', `Enterprise', `Creston', `Golden Delicious', `Ginger Gold', `Suncrisp', and `Goldrush'.